package java1224;

public class Java01 {
    public static void main(String[] args) {
        //变量和常量
        //变量：可以变化,可以更改
        int  a =2;
        System.out.println(a);
        a = 3;
        a = 5;
        a = 7;
        System.out.println(a);

        //常量：不能更改,用final关键字修改
        final int b = 6;

        //数字下划线
        int salary = 1_000_000_000;
        double d = 3.1415926_000_000_000;
        System.out.println(d);

        //赋值运算符,可以帮助自动类型转换
        int x = 3;
        double y = 3.0;
        x += y;

    }
}
